Method of reducing metallic oxides to metal without melting



- Dec. 9, 1941.1 T. NAGEL. T 2,265,812 f METHOD oF REDUCING METALLIC'oxIDEs To METAL WITHOUTYMEL'T'ING Filed April 8, 1.941*u ATTORNEYS.

Patented Dec. 9, A1941 UNITED STATES `1 PATENT- OFFICE 7 METHOD oFREDUCING Mamme oxnmsv Y v f 'ro METAL WITHOUT `limL'rnza f;

'meedere Nagel, Brooklyn, N. Y. y Applicaun April s, 1941, serial No.387.451

(cl. 15s-91) i 2' Claims.

My invention relates to a method for. reducing metallic oxide ore tometal.-

More speciiically my invention is directed to a method for reducingcrushed metallic oxide ore to metal wherein the crushed ore continuouslyslides by gravity downwardly along a series of alized in that thereducing gas entering the shaft is at such a temperature Yand the ratioof reducing gas to ore-andthe relative velocities ofthe gas and ore aresuch as to eiect reduction of the oxides to metal without melting. i

In the accompanying drawing wherein I have illustrated an embodiment ofmy invention:

Fig. 1 shows in sectional elevation an apparatus suitable for thepractice of the invention; and

Fig. 2 is a sectionon the line 2-2 of Fig. 1.

Referring to the drawing in detail: 2 designates an air sealed verticalshaft, equipped in its interior with a series of superimposed inclinedchutes 4. These chutes are disposed in alternating or zigzag fashion sothat the crushed metallic oxide ore (i` which is fed from conveyor linto a feed hopper 8 on topof the shaft, air seals thetop of the shaft2, the crushed ore beingA continuously fed by gravity to the series ofchutes down which it slides through ,the shaftv to the bottom thereof inAinclined alternatingA The discharge for the metal and gangue isdesignated l and in the drawing takes the form of lan air-sealed screwconveyor |72. It will be appreciated that by controlling the `continuousdischarge of the reduced ore by this conveyor the continuous movement ofthe furnace burden downwardly through theshaft 2 along the inclinedchutes 4 is regulated.

Adjacent its lower end the shaft 2 is provided with a gasgeneratingspace I4 communicating directly with the shaft 2,-as shown at |6.`

Hydrocarbons are introduced by pressure into this chamber fordecomposition to reducing' gas through valve controlled multiple nozzlesI8. At the bottom of the space- I4 isa porous bed 20 of suitablematerial such as Cobble stones, brick, coke, or other suitableaggregate.

22 designates a damper controlledinlet for air. under pressureintroduced at the bottom -of this porous bed.

The fuel admitted to the space I4 is a'hydrocarbon, asabovepoin'ted-out, and mayk take the form of. a liquid,` a vaporora gas.

The ratio of hydrocarbon to air {volume is readily controlled by thenozzle valves and lby the air inlet damper, these lbeing so'fadjustedthat after ignition a lhot reducing gas will be pro` duced continuouslyunder suiiicient pressure to cause the gas'continuously to 110W`upwardly of the reducing shaft 2' through the voids in the chargeofcrushedfore sliding by `gravity down" wardly of the shaft. x

The reducing gas isproducedat atei'np'erature I not lowerlthanapproximately 1650" F. and containscarbon dioxide in proportionytotheconn bined volume of carbon monoxide and molecular a hydrogenapproaching not more than 1 ,toi 5,;re'jspectively, While the r'atio ofcarbonlnonoxlde to molecularV hydrogen does not exceed approxi-vmatelylto 1 by volume.

As the crushed metallic oxide ore slides'down,

. wardly through the shaft 2 through the reduc# ing gas flowing upwardlythrough-the shaftrthe reducing gas will percolate :through the voids ofn i the mass of crushed orelacross the paths of the sliding ore. Theratej of movement of the ore, as.

above pointed out, is readily controlled by controlling the rate j ofdischarge of metaly andv gangue from the bottom of the shaft 2, whilethe ration of ore feedfto thev counte'riiowing gas volume feed is suchthat theore will nallyattain n the temperatureat which the .i'lnal phaseoi.' re

duction will transfer oxygen from the ore tothe active reducing gas.y y

top'of the shaft 2. The gasexhausting'through this outlet is at atemperature above 212 F.'and

contains carbon dioxide in proportion tojthel combined volume ofmorellcarbon monoxide and molecular hydrogen-approaching not' more thanapproximately l to 2, respectively.

Partial combustion occurs in the space il'ln 'I the presence of excesscarbon with the air which the voids of the plied by the nozzles i8 tomolecular carbon required for maintaining partial 'combustion, thecombustion products ubeing carbon monoxide with comparatively smaller-volume of carbon dioxide. The resulting. gas mixture con# y tainsoxidizing gas in proportionfto the volume of reducing gas approachingnot; more.than approximately 1 to 5, respectively, Aand the ratio ofcarbon monoxide to thevolumeuof,.lriolec'ulary hydrogen approaches notmore than approxi-y mately 1 to 1. y It will be seen, therefore, that inthis manner hydrocarbons are'fcontinuously converted-Tte a 26 designatesan exhaust gas outletlnear the- (2240 lbs.) of4 iron fromtwo long tonsof hema'- highly active reducing gas at the temperature required for thefinal phase of reduction of metallic oxides, after the ore bycounterflow heat exchange with the hot gas has been preheated to thetemperature required for this nal phase 5 of reduction. Following is anexample of the practice of my invention with respect to thewreduction ofiron ore to metallic iron. Itis understood, of course, I that this isamere illustrative example, inasmuch as other oxides may requiretemperature ranges and ratios of ore feed to gas volume feed differentfrom those presently to be set out. Let us consider the production ofone long ton tite (FezOs), this ore, we willassume, contains 50% iron.'I'he temperature range of reductionstarts at approximately 800 F. andthe final temperature reached by the burden is approximately 1800 F.

Three barrels of fueloll decompose .-to 91,000.. cubic feet (S. T. P.)135 B.t. u. .fuel value per cu. ft. gas, the gas having a temperature of2000 F. Top gas 91,000 cu; ft.` (VS. T. PJ, wet gas exhausted at 300F.is composed of approximately 16,800 cu. ft. steam and approximately74,200 cu. ft. dry gas of approximately 79k B.t. u.

, fuel value per cu. ft. Under the above conditions the heat balance asshown on drawing Fig. 1

approximatesz'y `Flnuimcn'(insana, Bmo'rxoNs AND Haar Bananen Furnace'burden-4480 lbs. ore (2240 lbs.

Fe+960 lbs. Ori-1280 lbs. gangue (rock) Furnace blast-91,000 cu.'ft (S.T. P.) l135 net B. t. u./C. Fs

Highly active reducing gas` at 2000 F.

` Heat input 15,750,000 B. t. u.

Gas mma/sisA 40 CO: 3% by volume, CO 21%v by volume Ha 25%by volume N251% byvolume l 45 100% aanstaan/C F.

Gaseous reduction reactions of liezCav to Fe Furnace heat. balance Dryads analysis f,

coz' 11.7% byvolme CO 17.5% by volume` 8.0% by volume N: 02.8% by volume79 net B. t.u./C. F.`

In the above,l example oil has been taken as the hydrocarbon from whichthe desiredhighly reactive lhot reducing gas isproduced by atomizing acontrolled supply of oil into a hot gas which is continuouslygeneratedby" partial vcombustion of carbon with air'in the gas generating-spaceof the furnace, the carbon being liberated through decomposing thel oilto molecular hydrogen and carbon most of which carbon supplies the fuelfor the above mentioned partial combustion.

It is to be understoodthat the process above 1 described may be variedasto its details without departingirom the spirit and scope of my ir-vvention. Y What I claim is: 1. The method oi' reducing metallic oxideore to metal, whichmethod comprises continuously sliding crushedmetallic oxide-ore by gravity in controlled flow'v in inclinedalternating paths through an air-sealedv shaft, simultaneouslyandcontinuously producing av hot CO+H2 reducing gas under pressure near'thelower end of the Y said shaft, and while confining the gas to the shaftflowing allv of the gas upwardly-through the voids of 'the mass ofcrushed oreacross the paths of said sliding crushed ore,` the" gastemperature, the ratio of gas to crushed ore and the relative velocitiesof the gas and crushed ore being such as continuously to effectprogressive reduction of the ore to metal4 without melting as theytemperature of the crushed ore progressively `in creases. y

- 2. Thefmethodof `reducing metallic oxidefore to metal, which methodcomprises continuously sliding crushed metallic oxide ore by gravity incontrolled flow1'in"inc1ined alternating paths throughfan air-sealedshaft, simultaneously and continuously producing a reducing gas near thelower end of the shaft, the gas beingproduced under pressure at atemperature not less than approximately 1650 F. and containing CO: in

volume relative to CO+H1 not more than approximately 1 to 5,respectively, and lCO in volume relativeto Hz not more thanapproximately 1 to '1, andwhile confining this gas to the airsealed'shaft flowing all of the gas upwardly through the voids Vof the porousmass of crushed ore across the paths thereof, the gas temperature, theratio of gas to ore and the relative velocitiesofthe gas and ore beingsuch that the gas after thus flowing through the voids of the mass o fcrushed ore will be at a temperature above 212` F. and contain CO2 involume relative to e CO-l-Hz of not more than approximately' lf-to 2,respectively, and progressive andcontinuous reduction of the ore tometal without melting will be effected as the temperature of the slidingcrushed ore progressively increases.

, THEoDoRE NAGL.

CERTIFICATE OF CORRECTION. Patent No. 2,265,812. December 9, 19).;1..v

THEODORE NAGEIJ.

It is hereby ertfed that error appears in the printed specificationofthe above numbered patent requiring correctionas' follows: Page l,second column, lne'O, for "ration" read -erat1o;,lne59, strike ont the lwor-d "more"; and that the said Letters Patent `should be read with thiscor` recton therein that the same may onoz'm to the record of the casein the Patent office. q

Signed and sealed this 15th day of January, A.- D. 1911.2.

v y Henry van Arsdale, (Seal) Acting ICozmnissioner of Patents.

